Ever since I updated to Snow Leapord on my mac book pro the computer has started to lag badly. I have used onyx to see if that could fix anything but still running slow. Since I used to be a windows user I am used to just trashing everything and doing a fresh install. I have no idea if this is the best option for a mac. Before I think about reinstalling I would like to know how I can check what could be slowing my computer down. I only have a basic knowledge of macs so any advice where I should look would be great. (I am a power user of PC but got annoyed of it just not working) If I do a reinstall what is the best way of going about it? Are there good methods so I don't lose all my programs and their product keys and some of their settings. i.e little snitch. I am just looking for any methods that I should follow before and during reinstalling. Thanks all.